DEVELOPMENT AND EVALUATION OF A NOVEL INSULIN ANALOGUE By Anand Khedkar M.Tech Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy Deakin University January, 2015 Acknowledgements First and foremost I would like to express my gratitude towards Biocon Limited, which gave me the opportunity to enrol for my Ph.D and letting me use the research facility. This would not have been possible without the encouragement from Dr. Harish Iyer, without whom I wouldn’t have done anything about realizing my long pending personal achievement. I would like to express my deep appreciation to my principal supervisor, Prof. Colin J. Barrow for his guidance and critique throughout the work. I would also like to thank him for his patience towards the progress of my work and putting up with the low frequency of my communication at times. My sincere gratitude goes to my associate supervisor Dr. Kedarnath Sastry for agreeing to become my supervisor although the area of our interests were different. I would like to thank him for the valuable discussions towards publications reviews of the work and guidance. Also, special thanks to Dr. Amarnath Chatterji from whom I have learnt a lot during my regular work as well as during my Ph.D. I would like to acknowledge the financial, academic and technical support of Deakin University, Waurn Ponds campus, particularly in the award of a PhD scholarship. I must say this is a great initiative Deakin University has taken which enables people like me who are working and allow them to fulfil their academic aspirations. I must mention that Shailendra Sonkar and Samir Deshpande who have become very good friends during my stay at Deakin and their good wishes have inspired me to carry through my last few months of my Ph.D. 4 I would like to thank Helen, Gayathri and Anuradha for their support for all the administrative issues and during my DIRI conference travels. Words fail to express my gratitude to my wife and parents for always being there and supporting me in many ways throughout my life. Without my father’s constant support and belief I would not have ventured into enrolling for my Ph.D at this juncture of my life. I would also like to make a special mention of Dr. Vivek Shenoy who sincerely believed that I deserved to complete my Doctorate and motivated me when things looked bleak. The list of people who motivated me to complete the journey is long and perhaps it would be impossible to mention every name here but I sincerely wish to thank each one of them for being there with me. A special mention for Dr. Harold Lebovitz, Dr. Alan Cherrington and Dr. Alexander Fleming from whom I have learnt a lot about diabetes and its management. Lastly and most important, I would like to thank the Almighty for the wisdom and perseverance that he has bestowed upon me during this research project and indeed throughout the life. 5 Table of Contents Acknowledgements ............................................................................................................................. 4 List of abbreviations ................................................................................................................... 16 Abstract ...................................................................................................................................... 18 Chapter 1 ............................................................................................................................................... 20 1.1 Introduction .......................................................................................................................... 21 1.2 Glucose metabolism: ............................................................................................................ 26 1.3 Development in Insulin treatment ........................................................................................ 27 1.4 Insulin Analogues: ............................................................................................................... 30 1.5 Alternate routes of insulin delivery ...................................................................................... 31 1.5.1 Inhalable Insulin ................................................................................................................... 31 1.5.2 Insulin transdermal patches .................................................................................................. 32 1.5.3 Oral Insulin .......................................................................................................................... 36 1.6 Protein modification ............................................................................................................. 44 1.6.1 Pegylation ............................................................................................................................. 44 1.6.2 PEGs for reducing Immunogenicity ..................................................................................... 45 1.6.3 Pegylated insulins................................................................................................................. 46 1.6.4 Pegylation for increasing half-life ........................................................................................ 46 1.7 Metabolism and elimination of PEG .................................................................................... 47 1.8 PEG toxicity ......................................................................................................................... 48 1.9 Absorption, Distribution, Metabolism and Elimination (ADME) ....................................... 50 1.9.1 Insulin degradation: .............................................................................................................. 51 1.10 Pegylated Insulin: A novel Insulin analogue: .................................................................... 53 6 1.10.1 Modification of Insulin: ..................................................................................................... 53 1.10.2 Effect of pegylation and tableting on structural integrity of the molecule ......................... 55 1.11 Aim of research .................................................................................................................. 55 Chapter 2 ............................................................................................................................................... 57 2.1 Background and Introduction ............................................................................................... 58 2.1.1 Solid solid mixing: ............................................................................................................... 60 2.1.2 Proteins under pressure ........................................................................................................ 61 2.1.3 Selection of pH for the experiment ...................................................................................... 65 2.2 Materials and Methods ......................................................................................................... 66 2.2.1 Pegylated insulin blend and tablet preparation and dissolution in solvents for solution studies............................................................................................................................................ 66 2.2.2 Scanning electron microscopy: ............................................................................................ 66 2.2.3 CD spectroscopy .................................................................................................................. 67 2.2.4 Thermal denaturation and melting curve data fitting ........................................................... 67 2.2.5 LC-ESI-MS data acquisition and analysis: .......................................................................... 68 2.2.6 Size Exclusion Chromatography: ......................................................................................... 68 2.2.7 Hydrogen Deuterium exchange: .......................................................................................... 68 2.3 Results and Discussion ......................................................................................................... 69 2.3.1 Pegylation does not alter structure of insulin. ...................................................................... 72 2.3.2 Formulation excipients may have a protective effect on pegylated insulin ......................... 76 2.3.3 Tablet formation stabilizes pegylated insulin structure:....................................................... 83 2.3.4 CD spectra of melting experiments on pegylated insulin tablets ......................................... 84 2.3.5 Globular fold of pegylated insulin is not affected by the tableting compression: ................ 86 7 2.4 Conclusion ........................................................................................................................... 90 Chapter 3 ............................................................................................................................................... 94 3. 1 Introduction ......................................................................................................................... 95 3.1.1 Metabolism of Polyethylene glycols .................................................................................... 95 3.1.2 Insulin processing................................................................................................................